What I found most interesting about Tim's turn around was his revelation that drinking had been the primary roadblock. Tim realized that his alcohol intake not only added more girth to his gut, but it led to his poor dietary decisions, and sapped his desire to work out.

Tim also went on to explain how his family was the main reason behind his decision to give up drinking, get healthy, and be a positive/healthy role model. And he looks better than he ever has at 45!

There is a lot of conflicting information and opinion out there about alcohol and its role in weight gain. If I had a penny for every person who's told me about all the research showing how a glass of wine a day can actually be heart healthy (but that same person goes on to drink four beers with their glass of wine a day), I'd have a lot of pennies!

Believe it or not, the extra calories from alcohol is not the primary reason people gain weight when the drink too much or too often. In fact, it's a distant third.

I don't want to be a total killjoy and say that you can never have a drink again, but I don't want you to sabotage all your hard work to be healthier with alcohol, either. Let's take a look at how alcohol can undermine your weight-loss efforts.

1. ALCOHOL DIMINISHES YOUR BODY'S ABILITY TO BURN FATWhen you drink alcohol, it's broken down into acetate, which your body burns for energy first – before any other calorie source or stored fat. So the energy that we expend when we have alcohol in our system is coming from the alcohol, not the other carbohydrates or fats which have to be stored if they're not burned.

In plain English? Alcohol squashes our ability to burn fat. In fact, a study published in the American Journal of Clinical Nutrition found subjects who consumed less than an ounce of alcohol over a 30-minute time period decreased their body's ability to burn fat by 73 percent!

2. ALCOHOL WEAKENS OUR INHIBITIONSMany of my clients tell me that they find themselves straying from their healthy eating habits when they've had a couple of drinks. When we drink alcohol, the functions our bodies use to tell us when we're full and when to stop eating are dulled. So not only are we more likely to give into temptation, we're also less likely to be able to tell when we've had enough.

In a UK Study that looked at alcohol's effect on calorie consumption, those who had the equivalent of two drinks ate up to 30% more. Building on that same principle, a Dutch study found that it took subjects longer to feel full when they drank alcohol before a meal, when compared to those who had a non-alcoholic beverage prior to eating. To put it simply, when we drink alcohol, we're more likely to eat too much of the wrong things.

3. ALCOHOL IS LOADED WITH CALORIESAlcohol has nearly twice as many calories per gram as protein or carbohydrates. We've all read about the surprising calorie counts of our favorite alcoholic beverages – 740 calories in a margarita! 210 in a cosmopolitan! But even if you cut out the sugary mixers and liqueurs used in your favorite cocktails, you're still consuming a lot of empty calories. Remember: alcohol is not an essential nutrient. Any calorie we consume from alcohol is completely valueless.

4. ALCOHOL PREVENTS ABSORPTION OF VITAL NUTRIENTSWhen we drink alcohol, the body shifts gears and focuses its energies on expelling the alcohol, which leaves little time for it to perform its other necessary functions, like processing vitamins and minerals and maintaining blood glucose levels, which are integral to maintaining a healthy metabolism. So not only does alcohol not have any nutrient value of its own, it also makes your body less able absorb and process nutrients that are valuable to you. So when we drink, those superfoods that we're trying to include in our diets become a whole lot less super.

5. ALCOHOL PREVENTS US FROM GETTING A GOOD NIGHT'S SLEEPIf you read my blog post on sleep's impact on our weight and bodies as a whole, you understand how important sleep is to our weight and overall health. Alcohol affects the quality of our sleep in a number of ways, from increased waking to shallower sleep, to pain due to heartburn caused by inflammation of your digestive system.

Not only that, but you can develop a dependence on alcohol to fall asleep, which actually works against you because it may help you fall asleep, but it won't help you get good quality sleep.

Check back every Wednesday for more insider tips from celebrity trainer Harley Pasternak on Hollywood's hottest bodies – and learn how to get one yourself! Plus: Follow Harley on Twitter at @harleypasternak